Active grille shutters (AGS) may be incorporated into vehicles in order to help meet increasingly strict fuel economy standards. Active grille shutters (AGS) are typically located proximate to a front grille of a vehicle, and may be selectively adjusted in order to increase or decrease the amount of fresh air entering an underhood area of the vehicle through the grille. AGS may be closed and remain closed when starting a cold engine to reduce cool air transfer from outside the engine compartment and therefore increase engine temperatures more quickly to reduce vehicle emissions and fuel consumption. At elevated engine temperatures, the grille shutters may be opened in order to increase the amount of cool air entering the engine compartment, thereby increasing engine cooling. At higher vehicle speeds, active grill shutters may automatically close to block airflow through the engine cooling system when supplemental cooling is not beneficial, thereby reducing vehicle drag and fuel consumption. In some AGS systems, the AGS may be controlled using position feedback sensors coupled to the grille shutters.
Because of the impact that the AGS system has on engine cooling, and consequently engine performance, exhaust emissions, and efficiency, a robust diagnostic for readily identifying potential degradation in the AGS system is desired. Numerous degradation modes are possible for an AGS system. In one example, the AGS may be stuck in a fixed position, rendering the grille shutters unable to be automatically adjusted responsive to engine operating conditions. In other examples, the mechanical linkages between the AGS grilles and the AGS motor may be damaged, or the AGS position sensor or the motor itself may be degraded. Other attempts to address diagnosing degradation of the AGS system include monitoring engine temperature response as the position of the active grille shutters are adjusted. One example approach is shown by Farmer et al. in U.S. Patent Application Publication 2013/0338870. Therein, Farmers describes a method for performing an extended diagnostic of an AGS system responsive to monitoring for a mechanical fault condition signal (e.g., mechanically broken or stuck AGS) and an indication that a temperature proximate the grille shutters is outside a threshold.
The inventors herein have recognized potential issues with such systems. Namely, such systems fail to address AGS operation degradation due to faulty AGS position sensors. By having to depend on a functional AGS position sensor to indicate a mechanical fault to even initiate the diagnostic, the diagnostic is in itself incomplete. Furthermore, when AGS system sensor or degradation occurs, completely disabling the AGS system foregoes any fuel consumption reduction advantages that may be preserved by continuing AGS operation in its current capacity.
One approach that at least partially addresses the above issues includes a method, comprising: in response to an output of a first light sensor positioned within a vehicle, behind active grille shutters (AGS), diagnosing a position of the AGS; and in response to the diagnosed position, adjusting an engine operating parameter. In this way, responsive to a change in a light level behind the active grille shutters, it may be determined whether or not the grille shutters are being adjusted as commanded.
In another example, a vehicle system may comprise active grille shutters positioned at a front end of the vehicle; a light sensor positioned within the vehicle, behind and proximate to the AGS; and a controller including non-transitory instructions stored in memory for: while commanding the AGS into an open and then a closed position, monitoring an output of the light sensor; diagnosing a position of the AGS in response to the monitored output of the light sensor relative to a threshold; and adjusting an engine operating parameter in response to the diagnosed position.
In this way, by utilizing a light sensor behind the AGS to diagnose a position of the active grille shutters, degradation modes of the AGS may be determined. These degradation modes may include, but are not limited to, mechanical degradation of the AGS system, which may include a degradation of the AGS motor, stuck or broken grille shutters, or degradation of mechanical linkages between the AGS motor and grille shutters. Additional degradation modes that may be identified include a degraded AGS position sensor, if the AGS system is so equipped. The technical result of using a light sensor to indicate degradation of the AGS system is that partial AGS degradation, where the AGS may still be able to be adjusted to a limited capacity, may be inferred. As a result, operation of the AGS may be continued, albeit in limited capacity, such that the fuel consumption reduction advantages may be preserved to the greatest extent possible. Further still, inferring the AGS position via a light sensor is more reliable over monitoring ambient temperatures and engine temperature changes with respect to an inferred AGS position, as engine temperature may not respond immediately to AGS position changes, and engine temperature may vary for numerous reasons. As a result, by utilizing an output of the light sensor while commanded the AGS into different positions, a position of the AGS may be more accurately diagnosed and a user may be notified if the AGS system needs to be serviced or replaced. The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.